[Fatal1ty]

4WD and 2WD: A rear sway bar makes the grip more consistent, with less grip.

2WD: I never use a sway bar in my B4.1 on dirt (clay, ...).
On carpet I only use it, when my car is to slow in fast turns and shicanes. Its also good when your rear suddently gripp off!

4WD: I got a Bmax, buts its similiar in setup like AE. Indoor in 99% I use a sway bar front and rear. Less traction rolls, also more consistent with less grip. Improove stability in fast turns and shicanes.
On dirt, I only use one in rear. More cornerspeed, easier out turns, harder over bumps/jumps!